Are shoppers tickled pink by strangely-coloured foods?

The eyes have it—colour plays a major role when it comes to the taste and perception of food.

Purple heritage potatoes and carrots are trendy with foodies, but some grocery shoppers may be reluctant to buy them because they're not used to seeing the produce in those less usual shades.

"We do some tasting experiments where we change the flavours and have it different than the colour and people are so influenced by the colour that it almost overrides what their taste buds might be telling them,'' says Dr. Phyllis Shand, professor and head of the department of food and bioproduct sciences at the University of Saskatchewan.

She says research has shown that colour can influence both how intense taste is perceived and whether we like the flavour of a food.

"I think it's because in terms of our brains, the colour centre is close to the centre for all of our senses so there's some interaction ... that's helping to make sense of all the information that the brain is being given at that one moment.''

While companies are no doubt aware that some shoppers will have a strong aversion to strangely coloured foods, that hasn't stopped many from experimenting with some odd concoctions.

Back in 2000, Heinz shook up the market with green ketchup, which was eventually followed by purple, pink, orange, teal and blue versions of the condiment. The gimmick lasted for several years before the product was discontinued.

More recently, a Loblaws store at Toronto's Maple Leaf Gardens, located near the epicentre of the city's gay pride events, showed its support in June with an array of psychedelic-looking fresh goods.

The meat department tinted the casings of the store-made pork breakfast sausages with food colouring, including shades of green, purple and yellow. The bakery pumped out multi-coloured bagels, cakes and cookies, and pizzas were festooned with such toppings as various coloured peppers, purple onions and black olives in a rainbow pattern.

"I can't stop chuckling, these are horrifying and amazing and I'm buying them,'' wrote one commenter on Reddit after seeing the sausages.

Another wrote: "I couldn't possibly stomach these. My brain wouldn't let me eat green meat.''

Burger buns seem to be favoured by food marketers these days for colourful makeovers.

Last October, Ace Bakery and Hero Certified Burgers teamed up with a Think Pink Burger in support of Breast Cancer Awareness Month. A pink bun was created using beet juice, while the beef burger was topped with raspberry goat cheese and pink slaw. For every pink bun sold in Ontario during the campaign, $1 was donated to the Canadian Breast Cancer Foundation, which in the end totalled more than $5,000, said Dante Di Iulio, marketing specialist for Hero Certified Burgers.

Consumers nervous about sampling the pink bun found it more acceptable when they learned how the pink colour was achieved, the company said.

Hero has also introduced a jet-black bun created by Ace Bakery, which is tinted with powdered bamboo charcoal.

"Most customers are definitely skeptical to try it, but once they bite into it, they fall in love. It's definitely our most photographed product on social media as well,'' wrote Di Iulio.

But their black burger buns are not the first. Burger King Japan promoted all-black burgers—with black buns, black cheese and black ketchup all made from squid ink and bamboo charcoal—in 2014 and 2015.

In the U.S. last fall, Burger King introduced the "Halloween Whopper'' with buns made black through the infusion of A1 steak sauce in the dough.

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In the spring, Burger King also launched the "Angriest Whopper,'' a burger dished up in a bright red bun baked with hot sauce.

McDonald's in China also recently marketed two sandwiches tied to the release of the film "Angry Birds'': a fried chicken sandwich with a fiery red bun and a pork sandwich with a green bun.

"Our modern-day society is very interested in new things all the time and so I think that what the fast-food companies are trying to do is give something new to appeal to people— and they may or may not have hit the right response depending on the market or where they are,'' says Shand.

"They're constantly trying to appeal to all of our senses and doing things I guess opposite to what people might expect is their way to get interest in their products.''